Invited Speakers

Abstract:
The detection systems, capable of detecting vapor traces of different molecules in the air exists on the market. Usually the instrument is big and expensive and needs trained operator. Hand-held detection systems are usually based on the array of differently modified cantilevers with optical detection system. This is big and difficult to integrate and must operate in a vacuum, so such systems are not appropriate for miniaturization. In addition, environmental influences like temperature, pressure, vibrations, etc., together with big size of the detection system limit the usefulness of the approach.
In this talk we will present a vapor trace detection system based on the array of differently modified comb capacitive sensors, where adsorption of target molecules change the relative dielectric constants of each comb capacitor for a very small amount that needs to be detected. Different modification layers adsorb preferentially different target molecules, while they reject the others. To be able to detect different target molecules, an array of 64 differently modified comb capacitors were integrated together with electronics, which is capable to detect extremely small capacitive changes using low-noise, integrated electronic detection system, which operates on the array in real time without multiplexing, thus provide the detection in real time. We will present important design steps for the low noise analog signal processing electronics together with appropriate DSP that make possible to achieve the sensitivity better than 0.04aF/Hz for the array of comb capacitive sensors. Using such electronic detection system, it is possible to reach the sensitivity better than 3ppt TNT molecules in N2 carrier gas. The measurements related to the sensitivity are in good agreement with the predictions from the circuit as well as system level simulations. The detection system measures the capacitances of a 64 differently modified sensors and thus provide the possibility to use pattern recognition technique to improve the selectivity. The latest measurement results of the sensitivity and selectivity to different target molecules will also be presented

About the Speaker:Drago Strle received the Ph.D. degree in 1991 from University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia, in the field of the design and synthesis of switched capacitor circuits. He has more than 30 years of experience in the field of design of analog and mixed signal ICs, especially low-noise and high-performance sensor interface circuits. Currently, he is Associate Professor at the University of Ljubljana, teaching microelectronic courses. His research interests focus on but are not limited to the design and test of mixed-signal integrated circuits, analog and digital signal processing, modeling and design of, high-performance interface circuits for MEMS, chemical and biological sensors. He has published many journal and conference papers.